The present invention relates to materials useful in electronics and, more specifically, to piezoceramic materials.
The materials are used in acoustics, hydroacoustics, ultrasonic delay lines, and filter technology.
It is known that the highest piezoactivity is revealed by compositions pertaining to morphotropic regions of binary and ternary systems of solid solutions. As the number of components in a system increases, the dimension of the morphotropic region is increased and the range of compositions having parameters of extreme values is broadened.
In the prior art piezoceramic materials comprising ternary systems of PbTiO.sub.3 -PbZrO.sub.3 -PbB'.sub.1-.alpha. B".sub..alpha. O.sub.3, wherein:
B' is Nb.sup.5+, W.sup.6+ ; PA1 B" is Zn.sup.2+, Mg.sup.2+, Co.sup.2+, Mn.sup.2+, Ni.sup.2+ ; PA1 PbTiO.sub.3 =30.0 to 52.5 PA1 PbZrO.sub.3 =25.0to 47.6 PA1 PbB'.sub.1-.alpha. B".sub..alpha. O.sub.3 =1.5 to 28.4 PA1 PbB'".sub.1-.alpha. B.sup.IV.sub..alpha. O.sub.3 =2.3 to 29.4 PA1 PbTiO.sub.3 =37.5 to 42.5 PA1 PbZrO.sub.3 =33.0 to 42.0 PA1 PbB'.sub.1-.alpha. B".sub..alpha. O.sub.3 =5.0 to 15.0 PA1 PbB'".sub.1-.alpha. B.sup.IV.sub..alpha. O.sub.3 =5.0 to 15.0 PA1 .epsilon..sub.33.sup.T =2,159 to 4,441 PA1 K.sub.p =0.605 to 0.722 PA1 d.sub.31 =(5.42 to 9.38).10.sup.-6 CGSE units.
.alpha. is equal to 1/2 for W.sup.6+, and 1/3 for Nb.sup.5+, with PA2 PbCO.sub.3 PA2 TiO.sub.2 PA2 ZrO.sub.2 PA2 Nb.sub.2 O.sub.5 PA2 WO.sub.3 PA2 Mg(OH).sub.2 PA2 ZnO PA2 MnCO.sub.3 PA2 MnO.sub.2 PA2 Co(OH).sub.2 PA2 Fe.sub.2 O.sub.3
the compositions pertaining to the morphotropic region, have the parameters shown in Table 1.
It follows from Table 1 that for many systems the values of the dielectric constant, the electromechanical force factor, and the mechanical Q-factor are insufficiently high, while the dielectric losses known for certain systems are excessively high.
Furthermore, in some cases, e.g. in the production of high frequency ultrasonic transducers, it is necessary to employ materials possessing low values of the dielectric constant .epsilon..sup.T.sub.33 at a relatively high electromechanical force factor K.sub.p. The prior art materials (see for example Table 1), however, do not comply with this requirement.